A memory cell array of three-dimensional structure has been developed to realize a next-generation non-volatile memory device. The memory cell array of three-dimensional structure includes a plurality of stacked word lines, and memory cells formed inside a memory hole piercing through the word lines. Furthermore, a select gate transistor is also provided in the memory hole to allow access to a specified memory cell. The select transistor preferably has the cutoff characteristic such that the off-current is effectively suppressed.